Milk drinkers could gain digestive health benefits by switching from milk containing the A1 protein, according to new research from Curtin University in Western Australia.

The research was independently peer reviewed and published in the European Journal of Clinical Nutrition (EJCN) by the Nature Publishing Group, and was funded by a grant from The a2 Milk Company Limited.

Associate Professor Sebely Pal from Curtin’s School of Public Health and lead researcher for the study said to date there had been no solid evidence to demonstrate that A2 milk had different gastrointestinal effects for humans than regular milk.

“The majority of the milk consumed in Australia contains the A1 protein and at present there is strong debate amongst health professionals and industry about the health effects of milk containing the A1 protein,” Associate Professor Pal said. “Until recently, only animal studies had examined the impact of A1 type beta-casein protein in cows’ milk, compared to A2 type,” she said.

“Curtin’s project is one of the first, randomised studies to look specifically at how the two milk proteins affect humans’ gastrointestinal health in ordinary milk drinkers,” Associate Professor Pal said.

Associate Professor Pal said a surprising finding in the study was that ordinary milk drinkers, who did not consider themselves to be milk intolerant, found they had slightly softer stools when they consumed A1 milk as opposed to A2 milk.

“This result may not be so important by itself, however these softer stools can be associated with increased abdominal pain, and this was highly significant,” Associate Professor Pal said.

Bloating and voiding difficulty were also analysed as measures of participant discomfort.

“Interestingly, a sub-group of eight people who said they were intolerant to ordinary milk, also reported gastrointestinal benefits from the A1 beta-casein free diet,” Associate Professor Pal said.

“These preliminary results are very important for medical science and require follow up in other studies in different populations, like those with perceived intolerance to ordinary A1 beta-casein containing milk or people with irritable bowel syndrome,” Associate Professor Pal said.

Associate Professor Pal said the researchers will be seeking opportunities for further research projects with larger groups into the differences between the A2 beta-casein protein and A1 beta-casein protein in dairy products and their potential impact on human health.

Since launching in 2007, the a2 brand of milk has gained more than 8 per cent of Australia’s fresh milk market share. It is the only company that produces milk with only the A2 protein.

Other milk brands have recently promoted the benefits of the A2 protein as a marketing tool. Food manufacturer Lion recently began using the claim “naturally contains A2 protein” on its Pura and Dairy Farmers milk brands. However, consumer group CHOICE claimed that the A2 health claim on Lion’s milk brands was a “marketing ploy”, because the milk also contained the A1 protein, which is thought to be associated with health problems.